DESCRIPTION: The investigators propose to develop a videokeratoscope to allow fast, accurate measurement of corneal aberrations and to improve a cross cylinder aberroscope to allow measurement of the wave aberrations of the cornea and the whole eye. They propose to then back calculate the aberrations of the other optical components of the eye, primarily the lens. This method will be applied to normal and post surgical eyes to quantify the aberrations of the normal eye and to predict the effect of surgical or pathological alterations in the corneal shape on the wave aberrations of the eye, and predict the effect of pupil size on these wave aberrations.